Users/tafadnav/artifac output variable (#5133)

* Update contribute.md

* Emit ResourceTypes variable with set of resource types downloaded

---------

Co-authored-by: Katy DeCorah <[email protected]>

Author: fadnavistanmay

docs/contribute.md

@@ -30,6 +30,8 @@ cd ./src
 ./dev.(sh/cmd) test # run unit tests before git commit/push
 ```
 
+To test the agent in a pipeline, follow the [self-hosted agent installation steps](https://learn.microsoft.com/en-us/azure/devops/pipelines/agents/windows-agent?view=azure-devops). You will use the agent built from source in the `_layout` folder at the repository root to run the `config` and `run` commands.
+
 ## Debugging
 
 The agent can be run in debug mode by providing the parameter `--debug` to the `run` command.

src/Agent.Plugins/Artifact/PipelineArtifactServer.cs

@@ -233,6 +233,7 @@ internal async Task DownloadAsyncV2(
         {
             VssConnection connection = context.VssConnection;
             BuildServer buildServer = new BuildServer(connection);
+            HashSet<string> resourceTypes = new HashSet<string>();
 
             // download all pipeline artifacts if artifact name is missing
             if (downloadOptions == DownloadOptions.MultiDownload)
@@ -264,18 +265,21 @@ internal async Task DownloadAsyncV2(
 
                 if (buildArtifacts.Any())
                 {
+                    resourceTypes.Add(PipelineArtifactConstants.Container);
                     FileContainerProvider provider = new FileContainerProvider(connection, this.tracer);
                     await provider.DownloadMultipleArtifactsAsync(downloadParameters, buildArtifacts, cancellationToken, context);
                 }
 
                 if (pipelineArtifacts.Any())
                 {
+                    resourceTypes.Add(PipelineArtifactConstants.PipelineArtifact);
                     PipelineArtifactProvider provider = new PipelineArtifactProvider(context, connection, this.tracer);
                     await provider.DownloadMultipleArtifactsAsync(downloadParameters, pipelineArtifacts, cancellationToken, context);
                 }
 
                 if (fileShareArtifacts.Any())
                 {
+                    resourceTypes.Add(PipelineArtifactConstants.FileShareArtifact);
                     FileShareProvider provider = new FileShareProvider(context, connection, this.tracer, DedupManifestArtifactClientFactory.Instance);
                     await provider.DownloadMultipleArtifactsAsync(downloadParameters, fileShareArtifacts, cancellationToken, context);
                 }
@@ -306,13 +310,17 @@ internal async Task DownloadAsyncV2(
 
                 ArtifactProviderFactory factory = new ArtifactProviderFactory(context, connection, this.tracer);
                 IArtifactProvider provider = factory.GetProvider(buildArtifact);
+                resourceTypes.Add(buildArtifact.Resource.Type);
 
                 await provider.DownloadSingleArtifactAsync(downloadParameters, buildArtifact, cancellationToken, context);
             }
             else
             {
                 throw new InvalidOperationException($"Invalid {nameof(downloadOptions)}!");
             }
+
+            // Create a variable to store the resource types of the downloaded artifacts
+            context.SetVariable("DownloadPipelineArtifactResourceTypes", string.Join(",", resourceTypes));
         }
     }